The synthesis and assembly of specific components of the mitochondrial respiratory membrane will be studied in the germinating spores of the fungus Botryodiplodia theobromae. The dormant spores of this organism contain an incomplete mitochondrial respiratory system which is re-activated early in spore germination through a series of biosynthesis and(or) assembly processes. The general objective of this proposed research project is to study the biosynthesis in vivo and in vitro of specific protein components of the respiratory membrane, to examine their incorporation into the mitochondria, and to learn whether they undergo post-translational modification in the process of being incorporated into the mitochondrial membranes. Several unidentified polypeptides which are accumulated in the mitochondria early in spore germination and which are antigenically related to cytochrome c oxidase will be examined as possible precursors to some of the subunits of this enzyme. The synthesis during germination of the chloroform-methanol-soluble subunit of mitochondrial ATPase will be measured and the metabolic requirements for its incorporation into the ATPase complex will be established. The synthesis of apocytochrome c during spore germination will be measured, and the kinetics and cellular site for insertion of the heme moiety will be determined. The physiological significance of specific methylation of cytochrome c will be examined. In vitro translation of messenger RNA from dormant and germinating spores and specific immunoprecipitation of the translation products will be employed to help identify possible precursors of respiratory membrane proteins and to evaluate possible mechanisms for incorporation of these exogenous proteins into the spore mitochondria. Comparisons will be made of the capabilities of messenger RNA from dormant and germinated spores to code for specific subunit polypeptides of respiratory enzyme complexes.